Conductor for electric furnaces



K. C. RANDALL AND H. A. TRAVERS.

CONDUCTOR FOR ELECTRIC FURNACES.

' APPLICATION FILED J-ULY I0, 1918.

1,435,256. Patented Nov. 14, 1922.

Patented Nov. 14, 1922.

UNITED STATES PATENT OFFICE.

KARL C. RANDALL, OF EDGEWOOD. AND HENRY A. TRAVERS, OF WILKINSBURG,

PENNSYLVANIA, ASSIGNORS T0 WESTINGHOUSE ELECTRIC AND MANUFACTUR- ING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONDUCTOR FOR ELECTRIC FURNACES.

Application filed July 10,

T 0 all whom it may concern:

Be it known that we, KARL C. RANDALL, a citizen of the United States. and a resident of Edgewood, in the county of Allegheny and State of Pennsylvania, and HENRY A. TRAVERS, a citizen of the Fnited States, and a resident of ilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Conductors for Electric Furnaces, of which the following is a specification.

Our invention relates to conductors and particularly to conductors of high currentcarrying capacity, such as leads for electric furnaces.

One object of our invention is to provide a conductor, of the above-indicated character that shall be light in weight, rugged and durable and of such open construction as to permit ventilation thereof.

Another object of our invention is to provide a flexible conductor that shall be, in general, of tubular formation and that shall comprise a plurality of side-by-side conductors in which uniform currents may flow, regardless of inductive effects thereon and that will retain its tubular formation in its flexed positions.

In connection with electric furnaces, or other devices using high currents and having movable members, such as electrodes to which it is necessary to conduct current, it is desirable to have flexible conducting means therefor.

Flexible conductors or connectors have been employed that have been constructed of a relatively large number of smaller conductors to provide the required flexibility and current-carrying capacity. These have usually been disposed side by side, in which relation they have been subjected to mechanical distortions, undue heating and other detrimental effects caused by mutual induction.

In practicing our invention, we provide a flexible conductor comprising a plurality of end-connected conductors spaced in sideby-side relation in the form of a tube or squirrel cage that is twisted helically from end to end in such manner that each of the component conductors is subjected to substantially the same amount of inductive effect from an adjacent conductor, thus in 1918. Serial No. 244,182.

suring a substantially equal current flow in the component conductors and eliminating objectionable features attending the use of ordinary conductors.

lVe further provide means whereby the conductor may retain its tubular form and, therefore, its improved electrical properties during its movement in flexed positions.

Fig. l of the accompanying drawings is a diagramn'latic side elevational view of an electric furnace employing our novel conductor; Fig. 2 is a plan view, partially in section, of one end of our conductor showing one of its attached terminal members and a co-operating supporting terminal member therefor; Fig. 3 is a view along line III-J11 of Fig. 2; Fig. l is a view, partially in elevation and partially in section, of a spacing ring employed in the conductor; Fig. 5 is a longitudinal elevational view of a conductor embodying our invention, parts being omitted for clearness; Figs. 6 and 7 are composite diagrammatic views and curves showing the effects of mutual induction upon the intensity of current in conductors that represent, respectively, priorart construction and our invention, and Fig. 8 is a longitudinal plan view, with parts broken away and omitted in order to more clearly illustrate one feature of our invention.

An electric furnace, comprising a main receptacle l, is provided with electrodes 2 (only one of which is shown) that are supported by a vertically movable frame or holder 3, the latter being provided with terminal members 4 between which and external stationary terminal members 5, flexible leading-in-conductors 6 are suspended. As indicated in Fig. 7, the conductors may be three in number, as in a three-phase system, and be connected to a source of supply (not shown) through conductors 8, bus-bars or other means.

Each of the conductors 6 comprises a plurality of similar smaller conductors 9 of substantially equal length and preferably of bare copper wire or cable but which may be of any other suitable material and covered with insulation, if desired. The conductors 9 are arranged in the form of a squirrelcage connected at each end thereof around the periphery of an annular sleeve or bushing 10. The sleeve 10 has an exteriorly threaded inner portion 11 that is also provided with longitudinal peripherally-spaced exterior slots 12 that receive the conductors 9 adjacent the ends thereof.

A frusto-conical 0r beveled outer portion 13 of the sleeve 10 provides seating means for the ends of the conductors 9 to which the latter may be securely'clamped by a hollow terminal member 14 that is interiorly threaded to co-operate with the threads on the sleeve 10 and has a beveled inner portion 15. The member 14 may also have projecting perforated blade portions 16 for engagement with similar blade portions 17 on either the terminal member 4 or the terminal-member 5, and may be connected thereto by bolts 18 and nuts 19.

Annular insulating ring members 20 having slots 21, corresponding in number and position to the slots 12, may be disposed at intervals along the interior of the conductor 6 to engage the conductors 9 and support the same in tubular and spaced relation. Peripheral grooves 22 in the members 20 intercept the slots 21 and receive cord 23,

tape, or other means for holding the conductors in the slots. The members 20 may be movably related to most of the conductors 9 to prevent buckling of the latter in flexed position and be clamped to one or more of the conductors to prevent longitudinal displacement of the same.

lVhen assembled, the conductor 6 is twisted from end to end through an angle of 360 or some multiple thereof, so that. when in position. each of the conductors 9 will extend through the magnetic field of the adjacent conductors 6 in the form of a helix. It may be understood that, if the conductors 6 were of straight squirrel-cage construction and parallel to each other, the remote conductors 9 of the same would be in a field of different intensity than the adjacent conductors 9. By threading through the field zone equal to the breadth of the conductor 6 in the manner described, each conductor 9 cuts substantially the same value of flux and is. therefore, reacted upon to the same extent. As a result, the induced electromotive forces are equal. causing uniform currents in all of the conductors 9 and thereby reducing the heating losses and other objectionable features usually attending ordinary conductors in multiple-inductive relation.

Since the conductor 6 may be relatively short. and slight flexure in one direction only he required of it. means for retaining the same in its twisted formation while disconnected from its terminals may comprise a chain of relatively hard and durable links of micarta. or other suitable insulating matcrial. Such a chain. as indicated by portions in Figs and 3 but shown more clearly in Figs. 5 and 8, may comprise links 2 L linked together by pins 25 and at the ends of the chain by pins 26, or other suitable means, the parts 24, 25 and 26 being preferably of non-conducting material or non-magnetic metal.

In Fig. 6, the relation of three mutually inductive conductors, each of a construction similar to our improved conductor but that are in electrical contact through their length or portions of it and the effect of such relations on the current distribution in each are shown. Viith breadth or diameter of the conductors in a direction along a transverse line passing through each of them as abscissae and current as ordinates. the latter may be readily of different values. as shown. In Fig. 7 the current will be substantially equal in all of the conductors 9. and. consequently, of uniform distribution in the conductors 6, as shown.

lVhile we have shown and described a particular form of our invention. many changes may be effected therein without departing from the spirit and scope thereof, as set forth in the appended claims.

We claim as our invention:

1. A hollow conductor comprising a plurality of spaced conductors in twisted relation and flexible means constituting part of said hollow conductor for maintaining said conductors in twisted relation.

2. A hollow conductorcomprising a plurality of spaced conductors in twisted relation and flexible means within said hollow conductor for maintaining said conductors in twisted relation.

3. A hollow conductor comprising aplurality of spaced separated conductors in twisted relation and flexible means Within said hollow conductor and constituting part thereof for maintaing said conductors in twisted relation.

4.. A hollow conductor comprising a plurality of conductors. transverse means for maintaining said conductors in spaced relation and flexible longitudinal means for maintaining said conductors in twisted relation.

5. A hollow conductor comprising a plurality of conductors. transverse means for maintaining said conductors in spaced relation and flexible means for maintaining said conductors in twisted relation and for limiting the longitudinal distortion of said conductors.

6. A flexible tubular conductor comprising a plurality of spaced side-by-side component conductors electrically connected at the ends, said flexible conductor being helically twisted between said electrical connections and means inside for maintaining said flexible conductor substantially tubular. and said component conductors in substantia ly the said twisted relation. under all operating conditions.

7 A flexible tubular conductor comprising to, and detached from, supporting means a. plurality of spaced side-by-side component therefor. conductors electrically connected at the ends, In testimony whereof, we have hereunto 10 said flexible conductor being helically twistsubscribed our names this 29th day of June, 5 ed between said electrical connections and 1918. v

flexible means for maintaining said flexible KARL C. RANDALL. conductor in its twisted form when attached HENRY A. TRAVERS. 

